You can bump up your relief pressure on the loader by shimming the relief spring, but it's set to a max for a reason. Even if your "careful" you can still bend things like cylinder rods, pull the nut off the end of the rod, blow hoses or piston seals, drag the engine down to bog or stall, as well as over work the hydraulic pump to failure. The way I see it; If Kubota could run a higher loader pressure, they would, so they could use it as a selling point. I know guys who have bumped up the pressure and for the most part have got away with it, but we're talking 100-200 PSI increase, which I believe is pretty marginal in the way of actual working performance improvement. Any more than that and your asking for trouble. Keep in mind no matter how gentle you're using the loader,
when you hit relief, you hit relief and that's the pressure you apply to the whole system. The hydraulic pump will continue to provide flow "infinitely" till the weakest link in the system "relieves" that pressure ( hyd pump case bursts, hose blows, valve comes apart etc.) or the engine stalls. That's why the relief valve is there and is set to a specific pressure, it's job is to be the weakest link, GOODBYE....../w3tcompact/icons/wink.gif